1. Field of the Invention
The present invention relates to a battery management system, and more particularly, to a remaining battery life prediction device for, for example, a lithium-ion rechargeable battery.
2. Description of the Related Art
It is required for rechargeable batteries that have been used in various devices represented by mobile devices to be provided with a battery management system configured to manage charge and discharge of the battery. An operating time of a device needs to be grasped more accurately particularly when the device is being operated, and a remaining battery life prediction device has been used for accurate detection.
A battery pack including a related-art remaining battery life prediction device is illustrated in FIG. 5. A remaining battery life prediction device 20 includes a CPU 21 configured to perform signal processing calculation, a RAM 22 to be used in the signal processing calculation, an ADC 23 configured to detect a battery voltage obtained by converting, with a level translator 26, a battery voltage of a rechargeable battery 6 per one cell, an ADC 24 configured to detect a voltage generated at a current sensing resistor 10 for detecting a current of the rechargeable battery 6, and a non-volatile memory 25 configured to hold data on, for example, characteristics of a battery in advance. The remaining battery life prediction device 20 is configured to obtain a remaining battery life based on a voltage of the rechargeable battery 6, a transferred charge amount obtained through coulomb counting with a current value of the rechargeable battery 6 measured with the use of the current sensing resistor 10, and the like. In order to predict a remaining life with high accuracy, it is required to measure the voltage and current of the rechargeable battery 6 with high accuracy.
In the related-art remaining battery life prediction device, a battery internal resistance is prepared in advance as a battery internal resistance model, and hence there is a problem in that the related-art remaining battery life prediction device cannot immediately deal with a variation in battery characteristics.
Moreover, in order to determine a voltage corresponding to a voltage drop based on the battery internal resistance, it is necessary to measure a current consumed by the battery, and there has been required a highly-precise current sensing resistor with a large allowable current amount in order to measure the current.